1. Field of the Invention
The present invention relates to a liquid crystal display device. The invention also relates to electrooptical apparatus using the liquid crystal display device.
2. Description of the Prior Art
Recently, the technique of fabricating thin film transistors (TFTs) on cheap glass substrates is being rapidly developed. The reason therefore lies in that the demand for active matrix liquid crystal display devices is increasing.
An active matrix liquid crystal display device is constituted in such a manner that a pixel portion is comprised of several hundred thousands to several millions of pixels which are matrix-wise disposed, a pixel TFT is disposed in each of the pixels, and the charges entering and leaving the pixel electrode connected to each pixel TFT are controlled by the switching function of the pixel
Recently, active matrix liquid crystal display devices are coming into wide use not only as the displays of the so far popularly used notebook type personal computers but also as the displays of desk top type personal computers.
Personal computers are required to display a plurality of pieces of information (including character information and image information) at a time: and thus, effects have been made to enhance the display ability of personal computers, that is, to enhance the image resolution and the realization of multi-gradation display (desirably, full-color display).
As a result of such enhancement in the display ability of personal computers, active matrix liquid crystal display device as the display device thereof is being improved. Thus, a digital driving type active matrix liquid crystal display device which is easy to effect interface with a personal computer and in which the high speed driving of the drivers can be achieved, and the display ability can thus be enhanced, is drawing attention.
To a digital driving type active matrix liquid crystal display device, digital video data are inputted from data sources such as personal computer. In the active matrix liquid crystal display device with digital drivers, it is necessary to provide a D/A conversion circuit (which is referred to as DAC: Digital-Analog Converter, in some cases). There are various kinds of D/A conversion circuits.
As one of the features of active matrix liquid crystal display device with digital driver, there can be pointed out the fact that the pixels corresponding to one line can be driven at the same time, in other words, line-sequential driving can be realized with relative ease.
Further, in the case of realizing the screen enlargement of the matrix liquid crystal display device and rendering the matrix liquid crystal display device highly precise and minute, the TN mode (twist nematic mode) using the known nematic liquid crystal cannot be said to be sufficient in its response speed.
Thus, recently, a report has been made of active matrix liquid crystal display device using an antiferroelectric mixed liquid crystal which has a V-shaped electrooptical characteristic, that is, which has a response speed faster by two or three figures than that of the nematic liquid crystal.
However, in the case this antiferroelectric mixed liquid crystal with a V-shaped electrooptical characteristic is used in an active matrix liquid crystal display device, the “image persistence” is more apt to take place than in the case of using nematic liquid crystal, thus leading to the problem of image deterioration.